Plasticizing chloroprene polymers



Patented a. is, 1946 msrrcrzmo. cnnoaornnua POLYMERS Arnold R. Davis, Riverside. Conn., asslgnor to American Cyanamid Company, N. 2., a corporation of Maine New York,

No Drawing. Application January '1, 1943,

Serial No. 471,605 4 12 Claims. 1

This invention relates to plasticizing polymers of chloroprene (chloro-2-butadiene-1,3)

It is known that certain products .made by polymerizing chloro-2+butadiene-1,3 presence of sulfur may be plasticized by milling with diarylguanidines, organic sulfides, disulfides, aromatic mercaptans, dithiocarbamates, Kanthates and the like. The unplasticized polymers are sometimes referred to under the trade name Neoprene.

The plasticizlng of Neoprene with chemical compounds outlined above has certain disadvantages such as high cost and, in the case of diarylguanidines, a prolonged aging period is required for maximum plasticity. Such disadvantages are obviously objectionable in the economical-manufacture of finished products in as short a time as possible.

It is an object ofthe present invention to pro-. vide new and improved materials for increasing the plasticity of polymers of chloro-2-butadiene- 1,3, particularly those polymers (or types of Neoprene) which can be plasticized by the prior art compounds referred to above. ject is to render the Neoprene highly plastic without extensive milling.

These and other objects are attained by milling the chloroprene polymers with asmall amount of organic base salts, of disubstituted dithiophosphoric acids, said salts having the following formula:

l uu= -x in which R1 is hydrogen or like Ra, R4 is hydrogen,

an aromatic, thiazyl or an aliphatic radical, X is SR3, NH2, --NHR4,

-NH-C-NH:, -NH-(I}NH| or -Nn-c-Nm R is an aliphatic radical and R is an aromatic in the A further obradical. These plasticizers include the guanidine,

biguanide, guanylthiourea, isothiourea and dlaryl Percent "Y" value plastlcizer ininches Neoprene GNcontrol None 0.100 p-myrlstoyl ethoxy isothiourea dibutyl l dithioghosphate 0.5 .070

Guenid e d butyl dithiofihos hate"-.. 0.5 .008 Guanylthioureo dibuty d tliiophoshate 0.5 .061

D ortho .olyl gusnidine dibutyl dithiohospna 0.6 .072 ono pnenyl guanidine dibutyl dithioghosphate 0. 6 070 B (2 cyanoethyl) amine salt of dibutyl dithiophcsphoric acid 0.5 .075 Diphenyl gusnldine di-isopropyldithlo- A 1 phosphate 5 .070 Aniline di-iso ropyl dithiophosphata.-. l 5 .053 p-Phenylene iguanidlne salt of dibutyl thiophosphoricacid 0.5 .070 s Aniline dibut ldithiophosphate 0.5 4 Guanidinedlopropyldithio hosphste. 0 5

Biguanide salt of dlbutyl d thiophosri iti u'arias?iazn'" any guan e o u y ohos horlc acid 0.5 .072 B s (et oxypropyl) amine salt ofdibutyl dithiophosphoric acid 0. 5 070 Cyclohexyl amine salt oi dibutyl dithiophosphoric acid 0. 5 008 Piperidine salt of dibutyl dithiophosphoric ac 0. 5 .066 Phenyl biguanide bis dibutyl dithio phosphate 0. 6 074 Phony blguanide diamyl tetra thiophosphate 0. 5 093 Pheny biguanide dlbutyl dithiophosphate 1.0 .OBl Aniline-dlcryandlamide-dibutyl dithiohos ho eacidreactionproduct 1.5 057 P eny bigusnide di-isopropyl dithiophosphate 1.5 .050

iline di-isopropyl dithiophoeplmte-dicyandiamldemction product 1.5 052 2 guanidine salts of the disubstituted .dithiophosphoric acids, the organic base being substituted for Y in the above formula: i

To illustrate the effectiveness of the plasticizers of the present invention, a 400-gram sample of Neoprene GN was milled for a total time of 10 minutes on rolls with an initial temperature of 50 C. and the sample was then cooled to room temperature. This sample was used as a control.

A similar sample of Neoprene GN was milled with the gradual addition thereto or a small amount of one of the plasticizers of the present invention, the rolls having an initial temperature of 50 C. and the total milling time being 10 minutes, the sample then being cooled to room temperature as before.

The milled samples were tested in 9. Williams plastometer for efiectivenes's of the compounds as plasticizers for the Neoprene. A 3-minute Y" value in inches at C. was employedforthe tests. The lowest Y value indicates the softest or most plastic stock. The results obtained were as follows:

Percent "Y" value plasticiur product Aminobenzothiazoie dibutyl dithioreaction phosphate-dicyandiamide phosphate D lauryi dithiophosphoric acid-anilinedicyandiamide reaction product A y alcohol-methyl hexanoi dithio- Phosphoric acid-aniline-dicyendiamdo reaction product Aniiine-dicyandiamida-meth l hexanol dithiophos horic acid react on roduct. Bis (cyanoet yl) amine-dlcyand amidemethyl hexanol dithiophosphoric acid reaction product Diorthotolyl guanidino-methyl heranol dithio hosphate 1.5 Phenyl iguanide methyl hexanol dithio phosphate l. 5 Auiline-dicyandiamida-but l ether of 2 diethylene glycol dith ophosphoric acid reaction product I i. Reaction product of aniiine-dicyandiamide-dithiophosphoric acid made from a mixture of amyl alcohol, paimitic acid and octadecanol see Aniline dicyandiamine disubstituted dithiophosphoric acid reaction products are believed to be the phenyl biguanide salts of the acids used and may be represented by the formula:

where F is alkyl, aryl or aralkyl as before. As pointed out in Application 471,606, the di-orthotolyl guanidine salt of dixylenol dithiophosphoric acid is also suitable as a softening agent,

The amount of softening agent employed may be varied and in general will be governed by the particular softening agent selected and the extent to which softening of the chloroprene polymers is desired. In general, the amount of plasticizer may be from about /2 to about 5% based on the weight of the chloroprene polymers. Larger in general, excessive amounts above 5% do not give correspondingly increased plasticity.

These plasticizers are also valuable fOr use in reclaiming vulcanized and scrap Neoprene, The Neoprene is merely ground in a tight cold mill and then milled with about 2 /2% of the plasticizer on rolls at about 40-50 C. until a suitable sheet is formed. The cured reclaim has almost the same properties as the original product. By mixing as much as 25% reclaim with 75% virgin Neoprene, products are obtaining possessing substantially the same physical properties as obtained with straight new Neoprene.

The plasticizers of the present invention may be prepared in any convenient manner but are preferably formed in accordance with the process set forth in my copending application Serial No.

in inches in the same manner.

amounts of the plasticizers may be used although,

Suitable modifications and changes may be made in the invention without departing from the spirit and scope thereof, the foregoing description being intended only by way of illustration except as defined in the following claims.

I claim:

l. A process of softening a rubber-like chloroprene polymer which comprises mixing the polymer with a minor proportion of its weight of a salt of a dialkyldithiophosphoric acid and a saltformlng organic base selected from the group consisting of the aliphatic secondary amines, the

mononuclear aromatic primary amines, the cycloaiiphatic amines, piperidine, guanidine, the monoand dimononuclear aryl guanidines, biguanide, the monomononuclear aryl biguanldes, guanylthiourea and isothiourea,

2. A process of softening a rubber-like chloroprene polymer which comprises mixing the polymer with about 0.5-5.0 percent of its weight of a salt of a dialkyldithiophosphoric acid and a salt-forming organic base selected from the group consisting of the aliphatic secondary amines, the mononuclear aromatic primary amines, the cycloaiiphatic amines, piperidine, guanidine, the monoand di mononuclear aryl guanidines, biguanide, the monomononuclear aryl biguanldes, guanylthiourea and isothiourea.

3. A method of softening a rubber-like chloroprene polymer which comprises mixing the polymer with a minor proportion of a phenyl-biguanide salt of a dialkyldithiophosphoric acid.

4. A method of softening a rubber-like chloroprene polymer which comprises mixing the polymer with a small amount of an organic base salt comprising an aniline-dicyandiamide-dialkyldithiophosphoric acid reaction product.

5. A method of softening a rubber-like chloroprene polymer which comprises mixing the polymer with a small amount of a phenyl biguanide salt of di(methylhexyl) dithiophosphoric acid.

6. A method of softening a rubber-like chloroprene polymer which comprises mixing the polymer with a small amount of an organic base salt comprising an aniline-dicyandiamide-di(methylhexyDdithiophosphoric acid reaction product.

7. A rubber-like plastic mass comprising a mixture of a. chloroprene polymer and a minor proportion of its Weight of a salt of a dialkyldithiophosphoric acid and an organic salt forming base selected from the group consisting of the aliphatic secondary amines, the mononuclear aromatic primary amines, the cycloaliphatic amines, piperidine, guanidine, the monoand dimononuclear aryl guanidines, biguanide, the monomononu- .clear aryl biguanides, guanylthiourea and isothiourea.

8. A rubber-like plastic mass comprising a mixture of a chloroprene polymer and about 0.5-5.0

5 ture of a chloroprene polymer and a minor proportion of its weight of a phenyl bizuanide salt of a dialkyldithiophosphoric acid. a

10. A rubber-like plastic mass comprising a mixture of a chloroprene polymer and a minor 5 proportion or its weight of .a salt comprising an aniline dicyandiamide dialkyldithiophosphoric acid reaction product. I v

11.'A rubber-like plastic mass comprising a proportion of its weight of'a salt comprising an aniline dicyandiamide di(methylhexyl)dithiophosphoric acid reaction product. i

ARNOLD R. DAVIS.

Certificate of Correction Patent No. 2,409,344. October 15, 1946. ARNOLD R. DAVIS It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows: Column 3, line 47, for the letter F read R; line 69, for the word obtaining read obtained; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 3rd day of February, A. D. 1948.

THOMAS F. MURPHY;

Assistant Oommissioner of Patents. 

